Improved process of hardening- talc, steatite



tater. 1 ggmm (Bf JAMESF. SELL, OF CAMBRIDGE, ASSIGNOR TO CHARLES HOUGH- TON, TRUSTEE, OF ROXBURY, MASSACHUSETTS.

Letters Patent No. 89,438, dated April 27, 1869.

IMPROVED PROCESS OI HARDENING- TALC, STEATITE, 81c.

The Schedule referred to in these Letters Patent and making part of the lime.

To all whom it may concern Be it known that I, JAMES F. SELL, of Cambridge,

in the county of Middlesex, and State of Massachusetts, have invented Improvements in the Treatment of Talc, Steatite, &c., to harden them; and I do hereby declare that the following'is a description of my invention, sufficient to enable those skilled in the art to practise it. Letters Patent of the United States, No. 71,919, were granted December 10, 1867, for the invention, by Henry Julius Smith, of a method of hardening talc, steatite, and other equivalent materials by heating them in a closed vessel, and in contact with carbon.

My invention is designedto effect the same purpose, and it consists in the following processes, viz:

- First, in heating in a crucible talc, steatite, silicate of aluminum, silicate of magnesia, or silicate of aluminum and magnesia, or articles formed therefrom, in contact with common salt, (chloride of sodium,) either alone or combined with alum, sulphate of aluminum, and then removing the tale, 8tc., or the articles formed therefrom, while hot and immersing them in a bath of sulphuric acid. 7

Second, in heating the said materials, or either of them, or articles formed therefrom, in a crucible, and then removing and immersing them while hot in a bath of sulphuric, nitric, muriatic, or other acid. After re moval from the said bath, the mat-erial,whethe'r treated by the first or second process, is washed with water, or with water containing an alkali to remove any adhering scale of the salt, or of the salt and alum, and any traces of the acid. 4

The salt, or the salt and alum, may be first fused in the crucible, or the talc, &c., and the salt, or the salt and alum may be placed together in the crucible, or the tale, 850., may be first heated and the salt, or the salt and alum may then be placed in the crucible.

The degree of heat applied to the tale, 850., whether salt, or salt and alum, is, or is not used prior to the immersion in the acid-bath, should be considerable but not up to a white heat.

' I claim the treatment of talc, or equivalent matter, or articles formed therefrom, by first beating them, with or without contact of salt, or salt and alum, and then immersing the tale or its equivalent while hot, in a sulphuric or other acid bath, substantially as described. I

JAMES F. SELL. Witnesses:

FRANCIS GOULD, 0. WARREN BROWN. 

